Solving Advent of Code 2019-03 with R and JavaScript.

[Disclaimer] Obviously, this post contains a big spoiler about Advent of Code, as it gives solutions for solving day 3.

[Disclaimer bis] I’m no JavaScript expert so this might not be the perfect solution. TBH, that’s also the case for the R solution.

## About the JavaScript code

The JavaScript code has been written in the same RMarkdown as the R code. It runs thanks to the `{bubble}`

package:https://github.com/ColinFay/bubble

## Instructions

Find the instructions at: https://adventofcode.com/2019/day/3

## R solution

### Part one

```
library(magrittr)
ipt <- scan( "input3.txt", what = character(), sep = "\n")
first <- strsplit(ipt[1], split = ",")[[1]]
sec <- strsplit(ipt[2], split = ",")[[1]]
directions <- function(ipt, x, y){
dir <- substr(ipt, 1, 1)
how_m <- as.numeric(substr(ipt, 2, nchar(ipt)))
if (dir == "R"){
x <- x + how_m
} else if (dir == "L"){
x <- x - how_m
} else if (dir == "U"){
y <- y + how_m
} else if (dir == "D"){
y <- y - how_m
}
return(list(x = x, y = y))
}
get_dir <- function(vec){
out <- data.frame(
x = 0,
y = 0
)
for (i in seq_along(vec)){
y_m_1 <- out$y[nrow(out)]
x_m_1 <- out$x[nrow(out)]
res <- directions(vec[i], x = x_m_1, y = y_m_1)
out %<>% rbind(
data.frame(
x = x_m_1:res$x,
y = y_m_1:res$y
)[-1,]
)
}
out$step <- 1:nrow(out)
out
}
out_a <- get_dir(first)
out_b <- get_dir(sec)
res <- merge(out_a, out_b, by = c("x", "y"))
res$path <- abs(res$x) + abs(res$y)
sort(unique(res$path))[2]
## [1] 386
```

### Part two

```
res$tot_step <- res$step.x + res$step.y
sort(unique(res$tot_step))[2]
## [1] 6486
```

## JS solution

Sorry today I didn’t have time to work on the JS solution… Finding the R solution was already quite a challenge :)

Here is the beginning of a code to solve the problem. Might get back to it later!

### Part one & Two

```
var res = fs.readFileSync("input3.txt", 'utf8').split("\n").filter(x => x.length != 0);
var first = res[0].split(",").filter(x => x.length != 0);
var sec = res[1].split(",").filter(x => x.length != 0);
function directions(ipt, x, y){
var dir = ipt.substring(0,1)
var how_m = parseInt(ipt.substring(1, ipt.length))
if (dir == "R"){
var x = x + how_m
} else if (dir == "L"){
var x = x - how_m
} else if (dir == "U"){
var y = y + how_m
} else if (dir == "D"){
var y = y - how_m
}
var ret = {x : x, y : y};
return ret
}
function get_out(vec){
var out = {
x: [0],
y: [0]
}
for (var i= 0; i < vec.length; i++){
var y_m_1 = out["y"][out[["y"]].length - 1 ]
var x_m_1 = out["x"][out[["x"]].length - 1 ]
var res = directions(vec[i], x = x_m_1, y = y_m_1)
out.x.push(res.x);
out.y.push(res.y);
}
return out
}
var dir_f = get_out(first);
var dir_s = get_out(sec);
```

## Discussion